Alliums

The ornamental onion that brings the border to life once the tulips have finished flowering

Alliums: the bridge between spring and summer

A magnet for bees and butterflies

From compact to majestic — which allium suits your garden?

Frequently asked questions about alliums

• When should you plant allium bulbs?
  It is best to plant ornamental allium bulbs in the autumn, from October to December, before the first frost. Alliums need the cold spell of winter to establish good roots in the spring and to flower in May and June. You can still plant them later, as long as the ground isn’t frozen.
• How deep should you plant allium bulbs?
  Plant allium bulbs at a depth of two to three times the height of the bulb — for large varieties such as ‘Gladiator’ or ‘Mount Everest’, this means approximately 15 to 20 centimetres deep. Smaller varieties should be planted at a depth of 8 to 10 centimetres. Leave a gap of at least 15 to 25 centimetres between the bulbs, depending on the size of the variety.
• Do alliums come back every year?
  Yes, most alliums are hardy and return every year. After flowering, always allow the foliage to die back naturally before removing it — this allows the bulb to store energy for the following season. After three to four years, the bulbs may become too crowded; this is when it’s time to dig them up, separate them and replant them.
• Can you plant allium bulbs in a pot?
  Certainly. Choose a deep pot with good drainage and use light, airy potting compost mixed with some coarse sand. Smaller varieties such as Cowanii, Jeannine or Sphaerocephalon are ideal for pots and balconies. Larger varieties require a pot at least 30 centimetres deep. Place the pot in a sunny spot and protect it from severe frost.
• What should you do with the foliage of alliums that is already turning yellow before flowering?
  This is a well-known characteristic of ornamental alliums: the foliage begins to turn yellow just as the flowers are in full bloom. The solution is simple: plant alliums amongst bushy perennials, ornamental grasses or hostas that will discreetly conceal the dying foliage whilst the flowers stand out above everything else.
• Are alliums suitable as cut flowers?
  Yes, alliums make excellent cut flowers. Their sturdy stems and long-lasting blooms make them ideal for vases, and the flower heads are also decorative when dried — in a dried flower arrangement or simply in the border, where they sway gently well into autumn.